Simulation Of Plastic Deformation Behavior Of Aluminum Thin Films By Quasi-continuum Method

In recent years,with the rapid development of nanotechnology,nano-materials in the electronic information,bio-engineering,aerospace,optoelectronic communications,medicine,pharmacy,defense and other high-tech cutting-edge areas have been market-oriented applications.So people are increasingly concerned about the material at the nano-scale characteristics.In this paper,the multi-scale calculation model of crystal orientation,grain boundary and indenter size was established by quasi-continuum method.The effects of crystal orientation,grain boundary and indenter size on the plastic deformation behavior of aluminum thin films were investigated.First,the nano-indentation process of FCC single crystal aluminum film under three different crystal orientations(x[111],y[1?10],z[1?1?2];x[1?10],y[111],z[1?1?2];x[110],y[001],z[1?10])are studied using the quasi-continuum method.And the load-displacement response curves of the film under different crystal orientations are presented.During the simulation,the microscopic deformation mechanism in the film is analyzed by local atomic diagram and equivalent strain distribution.The results show that the micro-mechanisms of the deformation in the film are different for different crystal orientations.In order to investigate the effect of grain boundary on the plastic deformation behavior of aluminum thin films,the nanoindentation process of aluminum thin films with a grain boundary or with no grain boundary was simulated by quasi-continuum method.It is found that the existence of grain boundary hinders the movement of dislocations and the slip of the crystals,and in order to further release the energy,the new Shockley dislocation will be nucleated at the sharp corners of the indenter and grain boundaries.Finally,in order to study the size effect of indenter in aluminum nanoindentation simulation,seven kinds of indenter widths were used to simulate multi-scale.The results show that the larger the width of the indenter and the larger the slope of the curve,the more difficult the loading of the aluminum film.With the increase of the width of the indenter,the critical load of the aluminum film is larger and the critical head depth is larger.The nano-hardness of the films shows a decreasing trend,and the aluminum film exhibits a significant size effect.